Urban sprawl effects on biodiversity in peripheral agricultural lands in calabar, nigeria

Journal of Environment and Earth Science www.iiste.org
ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online)
Vol. 3, No.7, 2013
219
Urban Sprawl Effects on Biodiversity in Peripheral Agricultural
Lands in Calabar, Nigeria
ATU, JOY EKO, OFFIONG RAPHAEL AYAMA & EJA, EJA I.
Department Of Geography and Environmental Science University Of Calabar, Nigeria.
E-Mail: joye.atu@gmail.com, ejaiwara43@gmail.com,raphyxx@yahoo.com
Abstract
The main objective of the paper is to determine the effects of urban sprawl on biodiversity in peripheral lands in
Calabar, Nigeria. The specific objectives of the study are: To examine the effects of farm size and farm density
on selected species in peripheral agricultural lands such as birds, butterflies and bumblebees and to compare
faunal diversity on farmlands within sprawl (FLWS) and farmlands outside sprawl (FLOS) areas. 20 farms were
sampled for the study, 10 in FLWS and 10 in FLOS. The relationship between farm size, tree diversity and
diversity of avian fauna (birds) on agricultural lands was tested with multiple correlation analysis. Result of the
analysis revealed that FLOS had more butterfly diversity with 42 (62.69 per cent) than FLWS with 25 (37.31 per
cent). It was also observed that the joint contribution of the two independent variables to the variance of bird
species in agricultural lands is positive with multiple correlation coefficient value of r = 0.50. This r value is
significant, implying that there is a significant relationship between farm size, tree diversity and the diversity of
avian fauna in agricultural lands. This finding implies that species diversity in agricultural lands are declining
while others, such as those in the Satyridae family are in danger of becoming extinct due to encroaching sprawl
development. It is therefore, recommended that eco-farming techniqus such as the cultivation of specific plants
that attract pollinators such as Ranvolfia volmitoria be integrated into farmlands.
Key words: Agricultural, Biodiversity, Peripheral, Urban sprawl
Introduction
Urban sprawl is one of the most challenging threats to biodiversity in the world today. Sprawl is a form of
development that typically occur in cyclical bands surrounding large urban centres. Often times urban sprawl
development originate as disconnected developments and single family homes established outside urban areas
well beyond city limits but usually within commuting distance to the city centre. Over time, the areas between
the disconnected settlements and the urban centre begin to be filled with residences, large ware outlets and other
businesses, parking lots and manicured lawns until a dense suburb is created. This newly developed areas have
been called “peri urban areas” (Imhoff, 2000), the “inter-metropolitan periphery” (Berry, 1990), and the
“exurban areas” beyond the suburbs called “fringe development” (Daniel, 1999) and “extendend places” Bureau
of the Census 2000) are all referred to as sprawl areas (Atu, Offiong, Eni, Eja & Esien 2012)
Thus, urban sprawl involves the conversion of open space, wetland, semi natural and natural vegetation and
agricultural land into built up developed land, therefore, the development of urban sprawl is not without
consequences on the native biota since land cover is positively correlated with species endemism, (Myers,
Mittermeir, Mittermer, Fonseca & Kent 2000). Hence, sprawl development threatens biodiversity directly
through habitat loss and indirectly through habitat fragmentation, degradation and homogenization of the native
biota.
The development of urban sprawl is linked to urban and suburban decline as economic activities move from
inner city region to Greenfield development sites at the suburbs. These Greenfield sites frequently offer lower
construction cost in the initial stages of development. The movement to new location is associated with
population growth, advances in transportation technology, and policies governing housing and infrastructure
(Mum, 1956).
Recently, in Calabar, 2002-2012, there has been outgrowth of Greenfield residences on the urban periphery
developed by the government, and the private sector for their workers or by property developers for rent or sale.
These development is consequent on the growth of the population of Calabar as a result of its new status as the
tourism/leisure destination of West Africa. This change in the size of the population and status of the city implies
pressure on agricultural lands and biodiversity because peripheral agricultural lands are converted to sprawl
development in order to accommodate the rapidly increasing urban population while the remaining agricultural
lands are worked more intensively to feed the immediate needs of the large urban population.
Prior to the recent sprawl development, the peripheral agricultural lands in Calabar are areas of high species
diversity, but, as these areas are modified, numerous species are declining such as Egretta garzetta, Little
egretta, Bostrycgia hagadash and Streptopelia decipiens. This is due to the fact that most species that have
adapted to agricultural lands require methods of non-intensive habitat management for their survival. Therefore,
the conversion of such farmed environment to urban sprawl is a threat to the rich fauna of these areas.

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Incidentally, agricultural lands and biodiversity are often considered to be mutually exclusive, hence, studies on
sprawl impacts on biodiversity are limited to the effects of urbanization on the environment (Kolankiewicz and
beck 2002);sprawl effects on agricultural land (Yohannes, 2002; Lopez’, Mitchell and Thomlinson 2001).
Inspite of these studies, the relationship between urban sprawl, loss of agricultural lands and the decline of
biodiversity, specifically, birds, butterflies and bumblebees has not garnered much attention in scientific
researches. It is this perceived limitation in scientific researches that this paper sought to study the effects of
biodiversity in peripheral agricultural lands in Calabar, Nigeria. It is based on the above that we asked the
questions: is there a difference in the diversity of species (birds, butterflies and bumblebees) between agricultural
lands impacted by sprawl and agricultural lands un-impacted and is there a difference in the diversity existing
within agricultural lands, that is, birds, butterflies and bumblebees among the different sprawl formations and
hypothesized that there is no significant relationship between farm size, tree diversity and the diversity of avian
fauna in agricultural lands.
Objectives
The main objective of the paper is to determine urban sprawl effects on biodiversity in peripheral agricultural
lands in Calabar, Nigeria. And the specific objectives are:
1. To examine the effects of farm size and farm density on selected species in peripheral agricultural lands
such as birds, butterflies and bumblebees.
2. To compare faunal diversity on farmlands within sprawl (FLWS) and farmlands outside sprawl (FLOS)
areas.
Literature
The decline in biodiversity as a result of the reduction and modification of agricultural lands has been
documented as evidence in the literature. This is because sprawl encroachment into peripheral agricultural
lands results in the loss of fertile land. Farmers, therefore, need to enhance the fertility of the land by
adding fertilizer, changing to new farm techniques or changing to more productive crops. This change in
prior farming techniques will definitely change the constitution of biodiversity that has adapted to the
former farm management. For instance Belfrage, Bjorklund and Salomonsson (2005) in their study on the
‘effects of farm size and organic farming on the diversity of birds, pollinators and plants in a Swedish
landscape’ discovered that more than twice as many bird species, butterflies, herbaceous plant species and
five times more bumblebees were found on the small organic compared to the large conventional farms.
The authors argued that altered management practice such as monocultures and intensification of
agriculture has influenced the number and demography of birds. This is in line with the findings of
Beecher, Johnson, Brandle, Case and Young (2002); where bird abundance in organic sites were found to
be more than two times higher than non -organic sites (that use fertilizer and herbicides).
In a similarly study, Luoto, Seppo, Jyrki and Juha (2003) linked agricultural production changes to
landscape fragmentation and species diversity. Based on their study on ‘the loss of plant species richness
and habitat connectivity in grasslands associated with agricultural change in Finland’, they argued that
development in agricultural production drives land-use changes and thus controls the capacity of
landscapes to maintain biodiversity. Hansen, Knight, Marzluff, Powell, Brown, Gude and Jones (2005)
also asserted that land use and land cover change due to sprawl is the primary cause of biodiversity loss in
the world. While Riley, Gary, Lee, Thomas, Lena, Rosi, Jacob, Robert and Sauvajot (2005) attributed the
decline of mammalian carnivores to urbanization (sprawl) and fragmentation. This assertion was made
based on the outcome of their research on ‘effects of urbanization and habitat fragmentation on Bobcats
and Coyotes in Southern California’ where urban areas were found to be less suitable in significant ways.
Riley, et.al (2005) studied the ecology of bobcats (Lynx rufus) and coyotes (Canis latrans) relative to
development in a fragmented landscape in southern California from 1996 to 2000. 50 bobcats and 86
coyotes were captured and radiocollared. The home ranges for 35 bobcats and 40 coyotes were
determined and their exposures to urban association were measured. Their findings show that even the
few animals that had almost no human development within their home range were vulnerable to human
related mortality.
In view of these assertions (Forys and Allen 2005) explored the relationship between sprawl and
biodiversity using a data set of ants species collected from forty six habitat patches located in the
increasingly urbanized Florida Keys in a study on, ‘The Impacts of Sprawl on Biodiversity: the Ant Fauna
of the Lower Florida Keys’. They quantified sprawl as the proximity of roads and amount of development
surrounding a habitat patch. Bait transect was used to identify 24 native and 18 non- native species of
ants. Their findings show that neither the overall number of native species nor the number of rare species

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was significantly correlated with the amount of development. They concluded that the native ant fauna of
the Florida Keys does not appear to be dramatically influenced by sprawl. However, they conceded that if
development increases, the number of non native ants may increase and many of these will decrease the
native ant diversity. Based on the study it can be concluded that sprawl is a precursor to the introduction
of invasive species in an ecosystem. This will eventually lead to the decline and loss of native species.
The work of Riley et. al., (2005) in Southern California Streams, contradicts the findings of Forys and
Allen (2005), by showing that urbanization was significantly correlated with alteration of stream habitat
and the introduction of invasive species. Riley, et. al (2005) also researched on the ‘effects of urbanization
on the distribution and abundance of amphibians and invasive species in southern California streams’.
They determined the distribution and abundance of native amphibians and exotic predators and
characterized stream habitat and invertebrate communities in 35 streams in an urbanized landscape north
of Los Angeles. Watershed development was measured as the percentage of area within each watershed
occupied by urban land uses. Streams in more developed watersheds had more exotic crayfish
(Procambarus clarkii) and fish and had fewer native species such as California newts (Taricha torosa)
and California tree frog (Hyla cadaverina) whose effects seemed particularly evident above 8 per cent
development. They thus, concluded that urbanization has significantly altered stream habitat in the region
which may enhance invasion by exotic species and negatively affect diversity and abundance of native
amphibians.
In another study on the European tree frog (Hyla arborea) in an agricultural landscape in Western
Switzerland, (Pellet, et. al. 2004) used a robust concentric approach based on permutation to evaluate the
impact of urbanization (sprawl) on the presence of the endangered tree frog in wetlands. The frequency of
1 traffic and 14 land use indices at 20 circular ranges (from 100m up to 2 km radii) around 76 ponds
identified in western Switzerland were analyzed. Their findings differ significantly from those of (Forys
and Allen 2005) by indicating that urban areas and road surfaces had a strong adverse effect on tree frog
presence even at relatively great distances (100m-1km). This implies that sprawl and traffic must be
considered when pond creation is an option in conservation management plans as is the case for the
European tree frog in Switzerland. Markovchick- Nicholls, Regan, Deutschman, Martin, Noreke and Hunt
(2008) looked at ‘relationships between human disturbance and wildlife land- use in urban habitat
fragments’ by tracking data (animal tracts and den or bed sites) on 10 animal species and information on
human activity and environmental factors associated with anthropogenic disturbance in 12 habitat
fragments across San Diego County, California. They examined the relationship among habitat fragment
characteristics, human activities and wildlife presence. No significant correlations of species presence and
abundance with per cent plant cover for all species or with different land use intensities for all species
except the oppssum (Didelphis virginiana), which preferred areas with intensive development was found.
Their result indicates that maintenance of habitat fragments in the form of farmlands is conservation
benefit to some animal species despite human activity and disturbance as long as the fragments are large.
Waltert, Mardiastuti and Muhlenberg (2004) findings differ significantly from those of Markovchick-
Nicholls,et. al. (2008) by showing that species richness decreased from natural forest and young
secondary to agro forestry systems and annual cultures. Although species richness was similar between
natural and young secondary forest, the number of endemic birds’ species was significantly lower in
second growth forest. Specifically, species composition gradually changed as the habitat changed from
natural to secondary forest to agroforestry systems and annual cultures despite the proximity of the farms
to near primary forest, the agro forestry supported only a few small frugivorous-nectarivorous species.
For Bell and Irwin (2002) sprawl is more a time dependent process that results in particular sprawling
spatial distribution that is visible at varying spatial scale. Human settlement is usually biased toward
resource rich areas resulting in clustered spatial distributions. Agreeing with (Bell and Irwin 2002),
Theobald (2003) pointed out that settlement pattern are highly clustered around important resources.
Hence as settlement expands with time the general level of human activity at broader scales increases and
human influence grows throughout the landscape by selecting more biologically rich habitat and
fragmenting landscapes thereby increasing conflicts with biodiversity.
The sprawl process according to Brown and Laband (2006) leads to higher levels of human activity at
broader spatial scales hence higher levels of impact on biodiversity. Brown and Laband (2006) also
asserted that it is the degree of activity and not variation in spatial distribution of activities that best
explains the variation in the proportion of endangering of native species. Hence the degree to which
settlements cluster or diffuse human distribution is not related to the percentage of endangered species in
an area when human activity levels remain constant. In response to (Brown and Laband 2006), Baldwin,

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222
Ray, Trombulak and Woolmer (2007) agreed that higher levels of activity inside any unit will lead to a
greater conflict with biodiversity but disagree with their conclusion that the patterns and process of sprawl
is not a leading cause of species imperilment.
Methodology
The types of data acquired for the study include: data on the spatial extent of farm lands within sprawl
(FLWS) and farmlands outside sprawl (FLOS) areas, farm sizes (FS) of farm lands, distance between
patchesm that is density (FD) of FLWS and FLOS and proximity of farm lands to built- up areas. The
total number and types of cultivated crops and tree species on FLWS and FLOS were collected.
Inventories of pollinators’ diversity (butterfly and bumblebees) and birds were also collected for the
study. Field observation, measurement and counting by the researcher was the main source of data for
birds, butterflies and bumblebees inventory, number and patch sizes of agricultural land, proximity of
agricultural lands to built -up areas and the types of crops cultivated. Data on the spatial extent of
agricultural land was extracted from Landsat ETM 1980 and SPOT Image of Calabar 2012. These data
sets were sourced from National Centre for Remote Sensing (NCRS) Jos, and the GIS Laboratory
Department of Geography and Regional Planning, University of Calabar, Calabar. Other sources of
information utilized for the study include journals, text books, dissertation on relevant study areas and the
internet which were sourced for literature and theoretical framework for the study.
A reconnaissance survey of the study area was undertaken from 3rd
-7th March, 2012 to determine
farmlands within and outside sprawl areas. The reconnaissance survey also created opportunities for
determining access points to the farms, line transect location, and obtaining permission from the farmers
to use their farms for the study. Samples were collected from the identified farms from May 14th
- August
14th
2012 (which is the peak of the farming season). Field measurement of farm sizes, farm density and
the distance of the farms to built- up areas within and outside sprawl areas were done by the researcher
with two assistants with the aid of a metric tape. This is to determine if sprawl has an effect on farm size
and crop types which were related to the diversity of birds, butterflies and bumblebees. The butterflies and
bumblebees were collected using baits made up of banana and table salt placed at sampled points (two
each of agricultural lands within sprawl and agricultural lands outside sprawl). Butterflies and bumblebees
that were attracted to the baits were collected using sweep nets as well as those on reproductive parts of
plants and placed in a killing jar containing cotton wool and chloroform to immobilize them. They were
then collected with fine forceps into labeled sample bottles and conveyed to the laboratory for
identification. Identification of the butterflies and bumblebees was done using Boorman’s (1991) method
and confirmed with paratypes identified in British museum and kept in the department of Zoology and
Environmental Biology laboratory, University of Calabar. Photographs of the butterflies and bumblebees
were taken immediately after collection and during identification with anti-blur technology super steady
shot Sony cyber- shot digital camera with ISO 300 film speed, 3xs zoom and face detection ability.
Number of butterflies and bumblebees collected is presented as mean values of two and four sampled
areas. For the bird census, all nestling and foraging birds within 100m of each sample point during a 5
minutes time frame were counted. The birds were sampled by sighting; Care was taken to observe the
appearance, habit, number of occurrence and vocal sound of each bird. Photographs were also taken
where possible in all sampled areas. Identification was made using Svensson and Grant, (1999) and
Perlos, (2002) methods. Flying birds were not included in the survey as they could not be said to use the
agricultural land (unless birds that feed during flight). Tree species were identified, counted and recorded
once on each sampled farm at the sampled points utilized for the birds, butterflies and bumblebees census.
All sampled sites were visited once a day for three consecutive days from 6.30am-9.30am for the
pollinator census. The mean of all observations was used in the data analysis. The SPSS (Statistical
Package for the Social Sciences) version 10.0 was used for all statistical analysis.
Analysis: The Watt Market was adopted as the Central Business District (CBD) and Mile 8 was assumed
to be the limit of the urban area. Thereafter, a 4 kilometere buffer zone in an Arc GIS environment was
created from mile 8 to delimit the peripheries of the urban area. The delineation of sprawl adopted the
format of Atu, Offiong, Eni, Eja and Esien (2012). Five areas out of the 8 identified areas that have
witnessed significant sprawl development in the past decade were purposively chosen for the study. Thus,
the sampled locations included Anantigha in Calabar South Local Government Area, Edim Otop/Satellite
town, Parliamentary Extension, Ekorinim and Esuk- Utan in Calabar, Municipality. The study areas were
further classified into Farmland Within Sprawl (FLWS) and Farmlands Outside Sprawl (FLOS) giving a
total of 10 sampled sites. Two farms were then selected from each of the sites as the sampled units, thus, a
total of 20 farms were sampled for the study. The multiple correlation analysis was utilized in testing the

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223
hypothesis. Birds in agricultural lands that have a frequency of 1 were classified as very rare, bird species
with a total frequency of two were classified as rare, and those with frequencies of 3-10 were classified as
common and frequencies of 11 and above were classified as abundant. The total number of bird species
and the average of all observation for butterflies and bumblebees with the total number of tree species
were used for the statistical analyses. The relationships were tested for the total number of bird species
and the total number of butterfly and the total number of bumblebee’s species in relation to the average
size and the farm patches. The relationship between farm size, tree diversity and diversity of avian fauna
(birds) on agricultural lands was tested with multiple correlation analysis. The formulas for the multiple
correlation analysis adopted from (Udofia, 2006) are presented as follows
=
. ∑ ∑ .
.∑ (∑ ) . . ∑ (∑ )
y =
.∑ ∑ .
.∑ (∑ ) . .∑ (∑ )
y =
. ∑ ∑ .∑
.∑ (∑ ) . .∑ (∑ )
=
. .
Where:
n = number of sampled farms
y= bird species on sampled farmlands
= farm size
= number of tree species (diversity)
r = correlation coefficient
Findings
A total of 20species of butterflies in five families of over 280 butterflies were identified during sampling (Table
1). Pieridae family had the highest occurrence of 30 (42.85 per cent), Lycaeidae 18 (27.7 per cent) occurrence
and the least occurrence was recorded in the Satyridae and Acraidae 3 (4.29 per cent). The highest species
occurrence was the Zizeeria kynssna species with 17 (14 per cent) followed by Mylothris sp with 29.99 per cent,
Acraea eponina 11.43 perc ent. Generally, FLOS had more butterfly diversity with 42 (62.69 per cent) than
FLWS with 25 (37.31 per cent). This finding implies that species of butterflies in agricultural lands are declining
while others, such as those in the Satyridae family are in danger of becoming extinct unless drastic conservation
measures are adopted. The mean number of butterfly species identified per sampled area is illustrated in Table 2.

Vol. 3, No.7, 2013
224
Table 1: Mean number of butterfly species identified in agricultural lands
N Family Genus/Species Mean number
collected
%
abundance
1
2
3
4
5
Pieridae
Nymhalidae
Lycaenida
e
Satyridae
Acraeidae
Leptosia medusa
Catopsilia florella
Mylothris rhodope
Mylothris chloris
Colotis evippe
Acraea eponina
Précis oenone
Hypolimnas
missippus
Hypolimnas sp
Euriphene tadema
Eunica amulia
Byblia achellia
Thermoniphas
micylus
Zezeeria knyssna
Spindasis sp
Spindasis
mozambica
Ypthima doleta
Bicycles asoctus
Ypthima sp
Bematistes vestalis
GRAND TOTAL
5.0
3.0
11.0
10.0
1.0
7.14
4.29
15.7
14.29
1.43
30.0 42.85
8.0
2.0
1.0
1.0
1.0
2.0
1.0
11.43
2.86
1.43
1.43
1.43
2.86
1.43
16.0 22.87
4.0
12.0
1.0
1.0
5.7
17.14
1.43
1.43
18.0 25.7
1.0
1.0
1.0
3.0
1.43
1.43
1.43
4.29
6.0 8.58
70.0 100.0

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225
Table 2: Mean distribution of butterfly species per sampled area
Family Species Edim Otop Anantigha Esuk Utan Ekorinim Parliamentary
Pieradae
Nymhalidae
Lycaenidae
Satyridae
Acraeidae
Leptosia medusa
Catopsilia florella
Mylothris rhodope
Mylothris chloris
Colotis evippe
Acraea eponina
Précis oenone
Hypolimnas
missippus
Hypolimnas sp
Euriphene tadema
Eunica amulia
Byblia achellia
Thermoniphas
micylus
Zezeeria knyssna
Zezeeria amulia
Spindasis sp
Spindasis mozambica
Ypthima doleta
Bicycles asotus
Ypthima sp
Bematistes vestalis
FLOS FLWS FLOS FLWS FLOS FLWS FLOS FLWS FLOS FL
WS
5
1
0
0
0
5
1
1
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
3
0
0
0
0
1
0
1
5
0
0
0
0
0
1
2
0
0
2
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
2
3
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
2
4
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
1
0
0
0
1
0
1
1
3
0
0
0
0
0
1
1
0
0
0
4
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Only two species of bumblebees were identified on sampled farms. FLOS had one species (specifically on FLOS
3 and FLOS 4) Table 1. FLWS had two Bombus species identified on FLWS 1 and FLWS 2. Both FLOS and
FLWS had 10 per cent occurrence of bumblebees. The two species of BOmbus identified during sampling are
illustrated in Plate 1. Bumblebees exists primarirly in the Northern hemisphere, few lowland species of
bumblebees exist (specifically in New Zealanad and Tasmania). Therefore, the occurrence of Bombus species on
these farmlands implies that specific plant(s) attract the bumblebees to the farms. A common characteristic of the
farms with Bombus species is the abundance of Ranvolfia vomitoria (illustrated in Plates 2a and 2b). Thus,
Ranvolfia vomitoria is considered in this research as an attractant to Bombus species. A bumblebee like butterfly
is a pollinator of the bee genus Bombus, in the Apidae family. There are over 250 known species and subspecies
in 15 subgenera, existing primarily in the Northern Hemisphere although there are more common in New
Zealand and Tasmania with few exception (there are a few tropical lowland species). Bumblebees are vital in the
production of certain crops, because they do pollinate plant species that other pollinators cannot by using a
technique called buzz pollination. For instance bumblebees are often placed in greenhouse tomato production
because the frequency of buzzing a bumblebee makes effectively releases tomato pollen

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Plate 1: Bombus species (bumblebees) in agricultural lands
Plate 2a: Ranvolfine volmitorie plant (Indian snake tree)

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227
Plate 2b: Ranvolfine volmitorie plant (Indian snake tree)
Two bird species identified and classified as very rare are Streptoppelia decipiens and Streptopelia
selegalensis Plate 3. Bostrycgia hagedash and Egretta egretta had a frequency of two and were classified
as rare. Other species such as Bueto bueto and Ploceus superciliosus were more common and abundant as
shown by their frequency of occurrence in Table 3.
Plate 3: Streptopelia decipiens (African mourning dove)

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228
Table 3: List of bird Species identified during sampling
Scientific name Common Name Frequency Classification
FLWS FLOS Total
Egretta garzetta
Bostrycgia
hagedash
Milvis migrans
migrans
Necrosyrtes
monachus
Bueto bueto
Numida
meleagris
Tunix sylvatica
Streptopelia
decipiens
Streptopelia
selegalensis
Hirundo
cucullata
Ploceus
cucullatus
Ploceus
superciliosus
Anomalospiza
imberbis
Little egretta
Hadada
Black kite
Hooded vulture
Common
buzzard
Helmeted
guinea fowl
Little button
quail
African
mourning dove
Laughing dove
Lesser stripe
swallow
Village (Black
headed) weaver
Compact
weaver
Parasitic
weaver
1
1
6
2
5
1
4
0
0
10
9
8
7
1
1
9
3
5
1
8
1
1
10
10
10
8
2
2
15
5
10
1
12
1
1
20
19
18
15
Rare
Rare
Abundant
Common
Common
Rare
Common
Very rare
Very rare
Abundant
Abundant
Abundant
Abundant
The multiple correlation analysis was utilized at 0.05and 0.01 significant level to test hypothesis two. The
dependent variable is the bird species, while farm size and tree species are the independent variables
(Table 4.14). The mean scores for patch size, tree species and bird species in peripheral agricultural lands
in Calabar were 1827.38, 2.25 and 3.35 (Table 4.15) respectively. Result of the multiple correlation
analysis indicate that the relationship between patch size and bird species is positive at r = 0.283 (Table
4.16). Tree diversity has a positive relationship with bird diversity on farmlands with r= 0.342. These
relationships are positive but not significant. On the other hand the relationship between patch size and the
diversity of trees on farm lands was very significant at the 0.01 significant level at r= 0.844 (Table 4.16).
Result of the multiple correlation analysis indicate that the relationship between farm size and bird species
is positive at r = 0.283 (Table 4.16). Tree diversity has a positive relationship with bird diversity on
farmlands with r= 0.342. These relationships are positive but not significant. On the other hand the
relationship between farm size and the diversity of trees on farm lands was very significant at the 0.01
significant level at r= 0.844 (Table 4.16). The contribution of the two independent variables (farm size
and tree diversity ) to the variance of birds was also examined by applying the multiple correlation
formula of:
=
. .
The result of the analysis indicates that the joint contribution of the two independent variables
to the variance of bird species in agricultural lands is positive with multiple correlation coefficient value of r =
0.50. This r value is significant, implying that there is a significant relationship between farm size, tree diversity
and the diversity of avian fauna in agricultural lands.
The coefficient of multiple determination r= 0.25 implies that only about 25 per cent of the variation of
birds on farmlands is as a result of the sizes of the farms and the number and species of crops cultivated.
The explained variation when 25 per cent is taken from 100 per cent may be attributed to other factors
such as proximity of farms to natural forest, distance of farms to built -up areas, abundance of butterflies
and other insects that the birds feed on and the maturity stage of the cultivated crops.

Vol. 3, No.7, 2013
229
Table 4: Results of multiple correlation of farm patch size, tree diversity and the diversity
of birds in agricultural land
Farm size TS BS
FS Correlation
Sig. (2-tailed)
N
1
20
.844**
.000
20
.283
.227
20
TS Correlation
Sig. (2-tailed)
N
.844**
.000
20
1
20
.342
.140
20
BS Correlation
Sig. (2-tailed)
N
.282
.227
20
.342
.140
20
1
20
The multiple correlation analysis was also used to examine the relationship amongst farm size, farm
density and selected species in peripheral agricultural lands such as birds, butterflies and bumblebees.
Result of the analysis shows that significant relationship exist among the variables. The relationship
between farmsize and farm density was significant at 0.01 level Table 5. A positive and significant
relationship also exist between farm size and butterfly species at r=0.553. The relationship between farm
size and bird species was positive but not significant at r=0.283. Generally, there was a positive
relationship amongst all inventoried variables. Farms with high butterfly diversity had high crop and
Bombus diversity.
TABLE 5: Results of multiple correlation of patch size and patch density with birds, butterflies and
bumblebees species in agricultural lands.
Farm
size
Farm
density
BS BFS BBS
patch size Correlation
Sig. (2-tailed)
N
patch density Correlation
Sig. (2-tailed)
N
BS Correlation
Sig. (2-tailed)
N
BFS Correlation
Sig. (2-tailed)
N
BBS Correlation
Sig. (2-tailed)
N
1
20
.704**
.001
20
.283
.227
20
.551*
.012
20
-.174
.463
20
.704**
.001
20
1
20
.005
.982
20
.353
.127
20
-.239
.306
20
.283
.227
20
.005
.982
20
1
20
.441
.051
20
.549*
.012
20
.551*
.012
20
.353
.127
20
.441
.051
20
1
20
.124
.603
20
-.174
.463
20
-.239
.306
20
.549*
.012
20
.124
.603
20
1
20
*. Correlation is significant at the 0.05 level (2-tailed)
**. Correlation is significant at the 0.01 level (2- tailed)

Vol. 3, No.7, 2013
230
Conclusion
The research demonstrates that sprawl has impacted negatively on biodiversity (birds and butterflies) in
agricultural lands and some species of butterfly such as those in the Satyridae family are already in danger of
becoming locally extinct, while Streptopelia decipien (African mourning dove) is on the verge of extinction in
the locality. Atu, et. al (2012) in their study on “the effects of urban sprawl on biodiversity in peripheral
agricultural lands in Calabar, Nigeria” argued that the expansion of sprawl into peripheral agricultural lands
reduce the spatial extent of farmlands and fragment them leading to reduce farm sizes and adaptations to urban
expansion leads to new forms of farm practices vis a vis crop types and farm management practices. Therefore,
the declining status of biodiversity on peripheral agricultural lands is attributed to changes in prior crop types
and farm management as a result of farmland loss due to sprawl. This is because fauna species on farmland have
adapted to prior regimes of farm practices, therefore, changes in these prior farming systems as a result of sprawl
development impact negatively on biodiversity as indicated by this research.
We therefore, suggest the adoption of eco- friendly farming systems such as planting of specific species of plants
that attracts birds, butterflies and bumblebees (e.g. Ranvolfia volmitoria) on agricultural lands.
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